Animal hairs having so-called tapered or sharpened ends are now used in various fields and articles, including brushes such as writing brushes and painting brushes made from hairs of weasels, raccoons and the like. Further, hairs such as those from Angora rabbits and the like have been mix-spun and incorporated into knitted or woven fabrics. Another well known use is in furs such as mink, fox, and the like.
These animal hairs, however, are very expensive, and extensive efforts have been made to produce synthetic fibers having their desirable characteristics have heretofore been proposed.
Means have been described for obtaining relatively good sharpened ends in synthetic fibers, as disclosed for example, in Japanese Patent Publication No. 40195/75 and in our Japanese Patent Application No. 105070/77, in which hydrolyzability of polyesters is utilized. Sufficient durability is obtained when tapered fibers so produced are used for writing brushes, painting brushes or the like, but these brushes are inferior to brushes of animal hairs as regards their ability to retain liquids. Accordingly, their characteristics and the ease of brush handling leave room for improvement.
Surprisingly, we have now found that when a fiber has a very special cross-sectional shape, the foregoing defects are eliminated and good brushes may be provided which are very suitable for writing and painting.
Furthermore, the fiber according to the present invention is excellent as compared to conventional fibers for formation into knitted or woven fabrics resembling those having animal hairs such as those of the Angora rabbit. Further, these fibers may be made into fabrics having a fur-like touch. Furthermore, it has now been found that fibers according to the present invention themselves have good touch and appearance.
Fibers according to the present invention are tapered or sharpened synthetic fibers each having a substantially pointed free end and including a tapered portion having an acute ridgeline extending longitudinally along the fiber surface.
The process for preparing animal hair-like synthetic fibers according to this invention includes the steps of subjecting at least one end of a bundle-like assembly of synthetic fibers to a decomposing or dissolving treatment in a treating solution to obtain fibers having tapered or sharpened ends. The fibers used in the process are characterized in that their cross-sections include at least one concave portion and at least one convex portion, which portions gradually taper off toward the outside from the center when viewed in cross section.
Fibers of this invention may be made into brushes comprising sharpened synthetic fibers having substantially pointed free ends, the fibers including tapered portions having a sharp or acutely curved ridgeline extending longitudinally along the body portion of the fiber, preferably to its tapered end.
Fabrics may be made which have naps of sharpened synthetic fibers having substantially pointed tip ends and including tapered portions having acute ridgelines as heretofore described.
According to the present invention fibers having long tapered or sharpened end portions and good liquid-retaining properties are very suitable for brushes or for the manufacture of knitted or woven fabrics or flocked fabrics having an animal hair-like or fur-like touch or appearance.
When fur-like fibrous structures are prepared from fibers of the present invention according to known techniques such as electrostatic flocking or sliver knitting, the fibers of the present invention have excellent fiber separability over conventional sharpened synthetic fibers having circular or flat cross-sections. This not only facilitates passage of the fibers through the processing steps, but also remarkably improves the appearance, luster and touch of the product.
The fibers of the present invention can be used in all fields where animal hairs have heretofore been used.
Specific embodiments of fibers according to the present invention will now be described with reference to the accompanying drawings. In the description which follows specific terms will be used for purposes of clarity, but these are not intended to define or to limit the scope of the invention, which is defined in the claims.